The present invention relates to machine tools in general, especially to grinding machines, and more particularly to improvements in means for mounting rotary material removing tools on rotary supporting members in the form of shafts, spindles and the like. Still more particularly, the invention relates to improvements in mounting means of the type wherein the material removing tool and the supporting member therefor are attached to each other end-to-end. The mounting means of the present invention can be used with particular advantage for separably securing grinding wheels, dressing wheels, profiling wheels, crushing rollers and like rotary members on spindles or analogous rotary supporting members.
Dressing apparatus which are used in or in conjunction with grinding machines often employ rotary spindles which serve to support dressing tools and are provided with relatively long and slender conical portions for introduction into complementary bores of dressing tools. A drawback of such mounting means is that the dressing tool cannot always be mounted in a predetermined axial position so that it is necessary to carry out secondary adjustments before the dressing tool is ready to treat the working surface of a grinding wheel. It is further necessary to safely secure the dressing tool against axial movement when the dressing apparatus is in actual use. Additional problems arise when the dressing tool is to be detached from its spindle because the relatively long and slender conical external and internal surfaces are normally moved into pronounced self-locking engagement with one another so that separation of such conical surfaces from one another requires the exertion of a large force.
In accordance with another known proposal, the spindle for a rotary dressing tool is provided with a cylindrical mandrel which must be inserted into a complementary large-diameter cylindrical bore of the dressing tool. Such proposal exhibits the drawback that, if the cylindrical bore of the dressing tool is not exactly coaxial with the cylindrical extension of the spindle, the tool is likely to wobble and to thus adversely influence the quality of the working surface of the workpiece (such as a grinding wheel) which is being treated thereby. Moreover, wobbling entails pronounced wear upon the parts and shortens the useful life of the dressing tool, of the spindle and of the grinding wheel.
A drawback which is common to each of the aforediscussed prior proposals is that conventional mounting of the dressing tool or grinding wheel on its spindle does not allow for convenient and rapid exchange of tools by automatic or highly automated tool changing devices. This is particularly important in automatic grinding machines wherein the frame often carries one or more magazines for spare grinding wheels and the machine further comprises an automatic tool changer which is designed to remove a spent or no longer used grinding wheel from the respective spindle, to transfer such wheel into the magazine and to deliver a fresh wheel from the magazine into the range of clamping means on the spindle. The complexity of the tool changing mechanism increases disproportionally with complexity of the means which is used to mount the tool on its spindle. The likelihood of establishment of a self-locking action between a slender conical external surface and an equally slender conical internal surface in a conventional mounting system for grinding wheels or analogous material removing tools is particularly troublesome insofar as automatic exchanges of grinding wheels are concerned. In fact, such types of mounting systems render it practically impossible to resort to a fully automatic tool changing device. In addition, the utilization of relatively long and slender conical surfaces prolongs the interval which is required for an exchange of tools because the tool must be moved axially through a considerable distance before it reaches a position from which it can advance in a direction toward the magazine.